多普勒组织显像动态检测猪慢性心肌缺血心功能

目的：进一步了解心肌冬眠的发生机制和组织多普勒各指标识别心肌早期缺血的敏感性。方法：10头正常家猪，开胸通过Ameroid环套扎猪冠状动脉左回旋支（LCX），建立慢性心肌缺血模型，于术前及术后2周、5周进行超声检查，并与病理结果对照。结果：10头猪中5头猪成功建立冬眠心肌模型，病理结果显示心肌细胞变性为主，除心内膜下小灶性梗死外，无明显梗死灶。超声检查发现术后2周、5周心脏各腔室大小正常，回声无改变，有2头猪局部收缩明显异常，部位及范围与伊文思蓝显示的LCX供血区范围一致。放置Ameroid环2周后，局部心功能指标左心室后壁（心内膜、心外膜）的心肌运动速度（Vendo、Vepi)、收缩期及舒张期运动速度峰值跨壁梯度（MVGm 、MVGm^-)、乳头肌短轴观左心室后壁均厚率均明显下降，术后5周Vendo、Vepi和MVGm 较术前下降，但术后5周与术后2周比较差别无显著性意义。整体心功能指标左心室短轴缩短率（FS）、射血分数（EF）无明显变化。时间运动曲线的最大值无论是阻塞区还是对照区，放置Ameroid环2周和5周后均无明显变化。结论：通过对局部心功能指标的检测可以敏感地反映心肌血流灌注状态、侧支循环的形成情况。心电图T波时心内膜运动速度、心肌运动跨壁梯度可反映心肌内膜下缺血。

Examination of the dynamic changes of heart function of pigs with chronic myocardial ischemia by Doppler tissue image

Objective To have a further realization of the mechanism of hibernating myocardium and sensitivity of DTI indexes in detection of early myocardial ischemia.Methods The left circumflex coronary arteries of 10 pigs were obstructed by Ameroid occlusions to make hibernating myocardium model.Echocardiography was performed before and 2 weeks or 5 weeks after operation and compared with histopathologic examination.Results Hibernating myocardium model was successfully established in 5 of 10 pig. The histopathology examination mainly showed myocardium denaturation with a little necrosis. At the 2nd and 5th week after operation ,the lumens of the hearts of model pigs were normal on echocardiography. Two pigs had abnormal regional contractile,the location and range of which were coincident with the risk area. After 2 weeks of ischemia, the endocardial,epicardial velocities and the myocardial velocity gradient(MVG) of the systolic stage and diastolic stage,the thickening of the posterior wall from short-axis view depressed significantly. Compared with pre-operation,the endocardial,epicardial velocities and MVG of the systolic stage were still lower at the 5th week,but no significant difference was seen between the 2nd week and the 5th week. The indexes of the whole heart function such as fraction shortening(FS) and ejection fraction(EF), didn't change with the time.The maximum valve of time velocity curve didn't change at the 2nd weeks and 5th weeks after the operation at both normal areas and risk areas.Conclusions The changes of endocardial velocity,MVG can reflect collateral circulation development and delineate early myocardium ischemia.